Graphene-drum pump and engine systems

ABSTRACT

The present invention relates to pump systems and engine systems having graphene drums. In embodiments of the invention, the graphene drum can be utilized in the main chambers and/or valves of the pumps and engines.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims priority to: provisional U.S. Patent ApplicationSer. No. 61/301,209, filed on Feb. 4, 2010, entitled “Graphene-Drum Pumpand Engine Systems,” which provisional patent application is eachcommonly assigned to the Assignee of the present invention and is herebyincorporated herein by reference in its entirety for all purposes.

TECHNICAL FIELD

The present invention relates to pump systems and engine systems havinggraphene drums.

SUMMARY OF THE INVENTION

Graphene membranes (also otherwise referred to as “graphene drums”) havebeen manufactured using process such as disclosed in Lee el al. Science,2008, 321, 385-388. PCT Patent Appl. No. PCT/US09/59266 (Pinkerton) (the“PCT US09/59266 Application”) described tunneling current switchassemblies having graphene drums (which graphene drums generally havinga diameter between about 500 nm and about 1500 nm). As described in thePCT US09/59266 Application, which is incorporated herein by reference,the graphene drum is capable of completely sealing the chamber formed bythe graphene drum (i.e., the graphene drum provides a complete seal tofluids inside and outside the chamber). A graphene membrane isatomically thin.

In embodiments of the present invention, graphene drums are employed inpump systems and engine systems, such as to replace pistons and valvesin conventional pumps and engines. Advantages of utilizing graphenedrums (and other electrically conductive drums that are atomically thin)in such systems include:

-   -   a. Higher power density (because graphene drum “piston/valves”        can operate in the MHz range (i.e., at least about 1 MHz)        instead of the approximately 100 Hz range of conventional pumps        and engines).    -   b. Higher efficiency (because graphene can withstand high        temperatures and no oil is required for graphene diaphragm        motion).    -   c. Quiet operation (because an operating frequency in the MHz        range is not perceived by humans).    -   d. Smaller size, as compared to conventional pumps and engines.    -   e. More precise fluid flow.

For instance, U.S. Pat. No. 7,008,193 (Najafi) (“the Najafi Patent”) isdirected to a MEMS-fabricated microvacuum pump assembly that utilizes adiaphragm made of a metal with a polymer layer on each side that is notatomically thin. Accordingly, the pump assembly is limited to kHzoperation (resulting in slow pump speed) and requires a relatively highvoltage to actuate (to overcome the inertia and stiffness of a thickdiaphragm). It is believed that, unlike graphene drums and otheratomically thin, electrically conductive drums, the MEMS-fabricatedmicrovacuum pump assembly of the Najafi Patent cannot maintain a highvacuum on one side. This would be disadvantageous because a vacuumenables a high electric field (and, thus, a high actuation force,between the gate and the diaphragm without arcing). The Najafi Patentalso appears to be a high wear device because the pump and valvemembranes of the MEMS-fabricated microvacuum pump assembly requirerepeated physical contact with other parts of the pump assembly tooperate properly. This is disadvantageous compared to embodiments of thepresent invention in that the present invention does not require thegraphene drum or other atomically thin, electrically conductive drum tocome in contact with other parts of the pump to work.

As used herein, a “gaphene-drum pump system” is a pump system thatutilizes one or more gaphene drums (such as a pump system that utilizesan array of graphene drums). A “graphene-drum pump” is a pump thatutilizes a graphene drum, such as a pump that utilizes the graphene drumto displace the fluid during operation of the pump. A “graphene-drumengine system” is an engine system that utilizes one or more graphenedrums (such as an engine system that utilizes an array of graphenedrums). A “graphene-pump engine” is an engine that utilizes a graphenedrum, such as an engine that utilizes a graphene drum to displace fluidduring operation of the engine.

As a graphene drum may be between about 500 nm and about 1500 nm indiameter (i.e., around one micron in diameter), millions ofgraphene-drum pumps could fit on one square centimeter of agraphene-drum pump system or graphene-drum engine system. In otherembodiments, the graphene drum may be between about 10 μm to about 20μm) in diameter and have a maximum deflection between about 1 μm toabout 3 μm (i.e., a maximum deflection that is about 10% to 15% of thediameter of the graphene drum). As used herein, “deflection” of thegraphene drum is measured relative to the non-deflected graphene drum(i.e., the deflection of a non-deflected graphene drum is zero).

In some instances, it is advantageous to use two or more graphenemembranes stacked on top of one another for use as a unit (such as foruse as a diaphragm). Such a stack of two or more graphene membranes arereferred to as a “multi graphene-membrane stack.” While each of theindividual graphene membranes of a multi graphene-membrane stack isatomically thin, the multi graphene-membrane stack itself generally isnot. For instance, a multi graphene-membrane stack of a dozen graphenemembranes generally would have a thickness of about 4 nm.

Alternatively, other types of electrically conductive membranes (alsoreferred to as “electrically conductive drums”) that are atomically thinmay be utilized in lieu of graphene membranes in embodiments of thepresent invention, such as, for example, graphene oxide membranes. Astack of two or more electrically conductive membranes are referred toas a “multi electrically-conductive-membrane stack.”

Moreover, the electrically conductive membranes or the multielectrically-conductive-membrane stack may include a thin (i.e., severalnanometers in thickness) protective coating to protect the electricallyconductive membranes from oxidation or corrosive fluids. For instance, aprotective coating of graphene oxide or tungsten can be applied to agraphene drum.

In general, in one aspect, the invention features a pump that includes acavity having a diaphragm. The diaphragm is operable to change thevolume capacity of the cavity. The pump further includes an upstreamvalve connected to the cavity. The upstream valve is operable to be inan open position such that fluid can flow through the upstream valveinto the cavity. The upstream valve is also operable to be in a closedposition such that fluid cannot flow through the upstream valve into thecavity. The pump further includes a downstream valve connected to thecavity. The downstream valve is operable to be in an open position suchthat fluid can flow from the cavity through the downstream valve. Thedownstream valve is also operable to be in a closed position such thatfluid cannot flow from the cavity through the downstream valve. At leastone of the cavity, upstream valve, or downstream valve of the pumpincludes an electrically conductive drum. The electrically conductivedrum is atomically thin.

In general, in another aspect, the invention features an engine thatincludes a cavity having a diaphragm. The diaphragm is operable tochange the volume capacity of the cavity. The cavity is operable toreceive a combustible fluid mixture that can ignite in the cavity toform a combusted fluid mixture. The engine further includes an upstreamvalve connected to the cavity. The upstream valve is operable to be inan open position such that the combustible fluid mixture can flowthrough the upstream valve into the cavity. The upstream valve is alsooperable to be in a closed position such that the combustible fluidmixture cannot flow through the upstream valve into the cavity. Theengine further includes a downstream valve connected to the cavity. Thedownstream valve is operable to be in an open position such that thecombusted fluid mixture can flow from the cavity through the downstreamvalve. The downstream valve is also operable to be in a closed positionsuch that the combusted fluid mixture cannot flow from the cavitythrough the downstream valve. At least one of the cavity, upstreamvalve, or downstream valve in the engine includes an electricallyconductive drum. The electrically conductive drum is atomically thin.

Implementations of the invention can include one or more of thefollowing features:

The engine can further include an igniter positioned inside the cavityto ignite the combustible fluid mixture in the cavity to form thecombusted fluid mixture.

The cavity can be operable to provide a pressure and a temperatureinside the cavity to ignite the combustible fluid mixture in the cavityto form the combusted fluid mixture.

The electrically conductive drum can have a thickness between about 0.3nm and about 1 nm.

The electrically conductive drum of the pump or the engine may be agraphene drum.

The electrically conductive drum can be a graphene oxide membrane.

The electrically conductive drum can have a protective coating.

At least one of the cavity, upstream valve, or downstream valve caninclude a multi electrically-conductive-drum stack of at least twoelectrically conductive drums.

The multi electrically-conductive-drum stack can have a protectivecoating.

The protective coating can include graphene oxide, tungsten, or acombination thereof. The protective coating can have a thickness lessthan about 5 nm. The protective coating can protect against oxidation,corrosive fluids, or both.

The cavity of the pump or the engine may include a first electricallyconductive drum. The upstream valve of the pump or the engine mayinclude a second electrically conductive drum. And, the downstream valveof the pump or the engine may include a third electrically conductivedrum. The first electrically conductive drum, the second electricallyconductive drum, and the third electrically conductive drum may all bepart of one continuous sheet of electrically conductive material.

The first electrically conductive drum can be a first graphene drum. Thesecond electrically conductive drum can be a second graphene drum. Thethird electrically conductive drum can be a third graphene drum.

The pump or the engine may further include a metallic gate. Theelectrically conductive drum may be operable to be pulled toward themetallic gate due to a voltage between the electrically conductive drumand the metallic gate. The metallic gate may include tungsten.

The diaphragm of the pump or the engine may be the electricallyconductive drum.

The diaphragm may be operable to move to a first position such that thecavity has a first volume capacity. The diaphragm may be operable tomove to a second position such that the cavity has a second volumecapacity. The first volume capacity may be larger than the second largercapacity.

The diaphragm may operable to cycle back and forth between the firstposition and the second position at a frequency of at least about 1 MHz.

The pump or the engine may further include a second cavity. Thediaphragm may be operable to change the volume capacity of the secondcavity. As the volume capacity of the cavity increases, the volumecapacity of the second cavity may decrease. As the volume capacity ofthe cavity decreases, the volume capacity of the second cavity mayincrease. The pump or the engine may further include a metallic gatelocated within the second cavity. The electrically conductive drum maybe operable to be pulled toward the metallic gate due to a voltagebetween the electrically conductive drum and the metallic gate.

The second cavity of the pump or the engine may be under vacuum.

The upstream valve of the pump or the engine may include theelectrically conductive drum. The electrically conductive drum may beoperable to cycle back and forth between the open position and theclosed position at a frequency of at least about 1 MHz.

The downstream valve of the pump or the engine may include theelectrically conductive e drum. The electrically conductive drum may beoperable to cycle back and forth between the open position and theclosed position at a frequency of at least about 1 MHz.

The electrically conductive drum of the pump or the engine may have adiameter between about 500 nm and about 1500 nm.

The electrically conductive drum may have a diameter between about 10 μmand about 20 μm. The electrically conductive drum, may have a maximumdeflection between about 1 μm and about 3 μm.

In general, in another aspect, the invention features an engine thatincludes a first cavity having a first electrically conductive drum. Thefirst electrically conductive drum is atomically thin and is operable tochange the volume of the first cavity. The engine further includes asecond cavity having a second electrically conductive drum. The secondelectrically conductive drum is atomically thin and is operable tochange the volume of the second cavity. The engine further includes apassage that allows fluid to flow between the first cavity and thesecond cavity. The engine further includes a heat exchanger operable tochange the temperature of the fluid. The change of temperature of thefluid is either: (a) cooling the temperature of the fluid as it movesfrom the first cavity to the second cavity and heating the temperatureof the fluid as it moves from the second cavity to the first cavity, or(b) heating the temperature of the fluid as it moves from the firstcavity to the second cavity and cooling the temperature of the fluid asit moves from the second cavity to the first cavity. The engine furtherincludes a metallic gate located in the first cavity. The firstelectrically conductive drum is operable to move away from the metallicgate to generate energy.

Implementations of the invention can include one or more of thefollowing features:

The first electrically conductive drum may be a first graphene drum. Thesecond electrically conductive drum may be a second graphene drum.

The first electrically conductive drum may have a diameter between about500 nm and about 1500 nm. The second electrically conductive drum mayhave a diameter between about 500 nm and about 1500 nm.

The first electrically conductive drum may have a diameter between about10 μm and about 20 μm. The second electrically conductive drum may havea diameter between about 10 μm and about 20 μm.

The first electrically conductive drum may have a maximum deflectionbetween about 1 μm and about 3 μm. The second electrically conductivedrum may have a maximum deflection between about 1 μm and about 3 μm.

The engine may further include a plurality of thermally conductivenanowires. The plurality of the thermally conductive nanowires may beoperatively connected to the cool cavity. The cool cavity may be thefirst cavity or the second cavity. The thermally conductive nanowiresmay be operable to cool the cool cavity.

Implementations of the invention can include one or more of thefollowing features:

The pump or engine of the above embodiments may further include aninsulating material. The insulating material may be silicon dioxide.

In general, in another aspect, the invention features a pump system thatincludes an array of pumps. The pumps in that array are pumps of one ormore of the above embodiments.

In general, in another aspect, the invention features an engine systemthat includes an array of engines. The pumps in that array are enginesof one or more of the above embodiments.

In general, in another aspect, the invention features a method ofoperating one of the pumps of the above embodiments.

In general, in another aspect, the invention features a method ofoperating one of the pump systems of the above embodiments.

In general, in another aspect, the invention features a method ofoperating one of the engines of the above embodiments.

In general, in another aspect, the invention features a method ofoperating one of the engine systems of the above embodiments.

In general, in another aspect, the invention features a method thatincludes opening an upstream valve to allow fluid to flow through theupstream valve to a cavity. The cavity is connected to a downstreamvalve that is in a closed position. The method further includes closingthe upstream valve. The method further includes reducing the volumecapacity in the cavity. The method further includes opening thedownstream valve to allow the fluid to flow from the cavity to throughthe downstream valve while maintaining the upstream valve in the closedposition. At least one of the cavity, upstream valve, or downstreamvalve includes a electrically conductive drum. The electricallyconductive drum is atomically thin.

In general, in another aspect, the invention features a method thatincludes opening an upstream valve to allow combustible fluid mixture toflow through the upstream valve to a cavity. The cavity is connected toa downstream valve that is in a closed position. The method furtherincludes closing the upstream valve. The method further includesreducing the volume capacity of the cavity. The method further includesigniting the combustible fluid mixture forming a combusted fluid mixturethat expands the volume capacity of the cavity. The method furtherincludes opening the downstream valve to allow the fluid to flow fromthe cavity to through the downstream valve while maintaining theupstream valve in the closed position. At least one of the cavity,upstream valve, or downstream valve includes a electrically conductivedrum. The electrically conductive is atomically thin.

In general, in another aspect, the invention features a method thatincludes flowing a fluid from a first cavity to a second cavity. Thefirst cavity has a first electrically conductive drum that moves todecrease the volume of the first cavity. The first electricallyconductive drum is atomically thin. The second cavity has a secondelectrically conductive drum that moves to increase the volume of thesecond cavity. The second electrically conductive drum is atomicallythin. The fluid is heated. The method further includes flowing fluidfrom the second cavity to the first cavity. The first electricallyconductive drum moves to increase the volume of the first cavity. Thesecond electrically conductive drum moves to decrease the volume of thesecond cavity. The fluid is cooled. The method further includes avoltage is applied to a metallic gate. The metallic gate is located bythe first electrically conductive drum or the second electricallyconductive drum. Energy is generated when that electrically conductivedrum (i.e., the first electrically conductive drum or the secondelectrically conductive drum located by the metallic gate) moves awayfrom the metallic gate.

Implementations of the invention can include one or more of thefollowing features:

The electrically conductive drums can be graphene drums.

In general, in another aspect, the invention features a valve thatincludes a cavity. The cavity has an electrically conductive membraneand an opening for flowing fluid though the cavity. The electricallyconductive membrane is atomically thin. The valve further includes agate operable to move the electrically conductive membrane between afirst position and second position due to a change in voltage applied tothe gate. When the electrically conductive membrane is in the firstposition, the electrically conductive membrane is located away from theopening such that fluid can flow freely through the opening. When theelectrically conductive membrane is in the second position, theelectrically conductive membrane is located at a predetermined distancefrom the opening such that fluid flow though the opening is restricted.

Implementations of the invention can include one or more of thefollowing features:

The valve can further include an electrical conductor located near theopening. When the electrically conductive membrane is located at or nearthe second position, the electrical conductor and electricallyconductive membrane are operatively connected to allow a current to flowtherebetween that is indicative of the location of the electricallyconductive membrane.

The valve may further include a controller operable to control thevoltage applied to the gate by utilizing the current to adjust the gatevoltage so that the electrically conductive membrane is located at thesecond position.

The current may be a tunneling current.

The valve can further include a resistor and a voltage source that areoperatively connected to the electrically conductive membrane and thegate. When the electrically conductive membrane is located near thesecond position, a current can operatively flow through the resistorthat passively lowers the voltage between the electrically conductivemembrane and the gate.

The valve can further include a capacitor sensor. The capacitor sensoris operatively connected to the electrically conductive membrane and thegate such that it may detect a change of capacitance between theelectrically conductive membrane and the gate that is indicative of thelocation of the electrically conductive membrane.

The valve can further include a controller operable to control thevoltage applied to the gate by utilizing the capacitance to adjust thegate voltage so that the electrically conductive membrane is located atthe second position.

The valve can be operable to prevent the electrically conductive memberfrom coming in contact with the gate.

The valve can further include a non-conductive member located betweenthe electrically conductive membrane and the gate. The non-conductivemember can prevent the electrically conductive membrane from coming incontact with the gate.

The electrically conductive membrane can be located at a distance suchthat stiffness of the electrically conductive membrane precludes theelectrically conductive membrane from deflecting to a degree in whichthe electrically conductive membrane comes in contact with gate.

The valve can further include a sensor and stabilizer system operablefor preventing the electrically conductive membrane from coming incontact with the gate.

The electrically conductive membrane may be a graphene membrane.

The predetermined distance may be about 1 nm.

The predetermined distance may be about 0.5 nm.

The predetermined distance may be about 0.3 nm.

The predetermine distance may be small enough to prevent most moleculesof the fluid from flowing though the opening and may be big enough toavoid wear of the valve.

The predetermined distance may be a range of distances from the opening.The predetermined distance may be a range of distances between about 0.3nm and about 1 nm. The predetermined distance may be a range ofdistances of about 0.7 nm±50%.

In general, in another aspect, the invention features a method ofoperating one of the valves of the above embodiments.

In general, in another aspect, the invention features a pump thatincludes one of the valves of the above embodiments.

In general, in another aspect, the invention features a pump of one ofthe above pump embodiments that includes one of the valves of the abovevalve embodiments.

In general, in another aspect, the invention features a method ofoperating one of the pumps of the above embodiments.

In general, in another aspect, the invention features a device thatincludes a pump. The pump includes a cavity having a diaphragm. Thediaphragm is operable to change the volume capacity of the cavity. Thepump further includes a first valve connected to the cavity. The firstvalve is operable to be in an open position in which fluid can flow (a)through the first valve into the cavity and (b) from the cavity throughthe first valve, depending upon the pressure differential across thefirst valve. The first valve is further operable to be in a closedposition in which fluid cannot flow (a) through the first valve into thecavity and (b) from the cavity through the first valve, regardless ofthe pressure differential across the first valve. The pump furtherincludes a second valve connected to the cavity. The second valve isoperable to be in an open position in which fluid can flow (a) throughthe second valve into the cavity and (b) from the cavity through thesecond valve, depending upon the pressure differential across the secondvalve. The second valve is further operable to be in a closed positionin which fluid cannot flow (a) through the second valve into the cavityand (b) from the cavity through the second valve, regardless of thepressure differential across the second valve. At least one of thecavity, first valve, or second valve includes an electrically conductivedrum. The electrically conductive drum is atomically thin.

Implementations of the invention can include one or more of thefollowing features:

The device may be operable as a speaker. The device may be operable as acompact audio speaker.

The electrically conductive drum may be a graphene drum.

The graphene drum may be operable for producing an audio signal having afrequency in the audio frequency range. The frequency may be betweenabout 20 Hz and about 20 kHz.

The graphene drum may be operable for producing an audio signal having afrequency in the audio frequency range by alternating the flow of airthrough the pump in a first direction and a second direction. The firstdirection of the air flow may be flowing the air through the firstvalve, into and through the cavity, and through the second valve. Thesecond direction of the air flow may be flowing air through the secondvalve, into and through the cavity, and through the first valve. Therate of alternating the flow of air may be the frequency of the audiosignal.

The device may be operable for medical applications.

The device may be operable for drug delivery.

The device may be operable as a heart pump.

The device may be operable for electronic applications.

The device may be operable as an ink pump.

The device may be operable as a fan.

The device may be operable to flow the fluid in a first directionthrough the first valve, into and through the cavity, and through thesecond valve, while the device is not operable to flow the fluid in asecond direction through the second valve, into and through the cavity,and through the first valve.

In general, in another aspect, the invention features a method ofoperating one of the device of the above embodiments.

There has thus been outlined, rather broadly, the more importantfeatures of the invention in order that the detailed description thereofmay be better understood, and in order that the present contribution tothe art may be better appreciated. There are additional features of theinvention that will be described hereinafter.

In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of otherembodiments and of being practiced and carried out in various ways.Also, it is to be understood that the phraseology and terminologyemployed herein are for the purpose of the description and should not beregarded as limiting.

DESCRIPTION OF DRAWINGS

FIG. 1 depicts a perspective view of the graphene-drum pump system.

FIG. 2 depicts a close-up of a graphene-drum pump (in the graphene-drumpump system of FIG. 1) in exhaust mode.

FIG. 3 depicts a close-up of a graphene-drum pump (in the graphene-drumpump system of FIG. 1) in intake mode.

FIG. 4 depicts a graphene-drum internal combustion engine in ignitionmode.

FIG. 5 depicts a perspective view of a graphene-drum Stirling enginesystem.

FIG. 6 depicts a side view of the graphene-drum Stirling engine systemof FIG. 5.

FIG. 7 depicts an alternative embodiment of a graphene-drum pump system.

FIG. 8 depicts the graphene-drum pump system of FIG. 7 with the graphenedrum in a different position.

FIG. 9 depicts a further alternative embodiment of a graphene-drum pumpsystem.

DETAILED DESCRIPTION

In an embodiment of the present invention, one or more graphene drumscan be utilized in a pump system. FIG. 1 depicts a graphene-drum pumpsystem 100 that has an array of graphene-drum pumps 101 (as illustratedthere are nine graphene pumps 101 in FIG. 1). As oriented in FIG. 1, thetop layer 102 is graphene. The top layer is mounted on an insulatingmaterial 103 (such as silicon dioxide).

FIG. 2 depicts a close-up of a graphene-drum pump 101 in thegraphene-drum pump system 100 of FIG. 1. Graphene-drum pump 101 utilizesa graphene drum as the main diaphragm (main diaphragm graphene drum201). The main diaphragm seals a boundary of the cavity 202 of thegraphene-drum pump 101. The cavity is also bounded by insulatingmaterial 103 and a metallic gate 203 (which is a metal such astungsten). The metallic gate 203 is operatively connected to a voltagesource (not shown), such as by a metallic trace 204. The main diaphragmgraphene drum 201 can be designed to operate in a manner similar to thegraphene drums taught and described in the PCT US09/59266 Application.

The graphene-drum pump also includes an upstream valve 205 and adownstream valve 206. As illustrated in FIG. 2, upstream valve 205includes another graphene drum (the upstream valve graphene drum 207).The upstream valve 205 is connected (a) to a fluid source (not shown) bya conduit 208 and (b) to the cavity 202 by conduit 209, which conduits208 and 209 are operable to allow fluid (such as a gas or a liquid) toflow from the fluid source through the upstream valve 205 and into thecavity 202. The upstream valve 205 also has a cavity 210 bounded (andsealed) by the upstream valve graphene drum 207, the insulating material103, and upstream valve gate 211. The upstream valve graphene drum 207can be designed to operate in a manner similar to the graphene drumstaught and described in the PCT US09/59266 Application. For instance,the upstream valve 205 can be closed or opened by varying the voltagebetween upstream valve graphene drum 207 and upstream valve gate 211.When the upstream valve 205 is closed, van der Waals forces willmaintain the upstream valve graphene drum 207 in the seated position,which will keep the upstream valve 205 in the closed position.

As illustrated in FIG. 2, the downstream valve 206 includes anothergraphene drum (the downstream valve graphene drum 212). The downstreamvalve 206 is connected (a) to the cavity 202 by a conduit 213 and (b) toa fluid output (not shown) by conduit 214, which conduits 213 and 214are operable to allow fluid to flow from the cavity 202 through thedownstream valve 205 and into the fluid output. The downstream valve 206also has a cavity 215 bounded (and sealed) by the downstream valvegraphene drum 212, the insulating material 103, and downstream valvegate 216. The downstream valve graphene drum 212 can be designed tooperate in a manner similar to the graphene drums taught and describedin the PCT US09/59266 Application. For instance, the downstream valve206 can be closed or opened by varying the voltage between downstreamvalve graphene drum 212 and downstream valve gate 216. When thedownstream valve 206 is closed, van der Waals forces will maintain thedownstream valve graphene drum 212 in the seated position, which willkeep the downstream valve 206 in the closed position. Generally,upstream valve gate 211 and downstream valve gate 216 are synchronizedso that when the upstream valve 205 is opened, downstream valve isclosed (and vice versa).

FIG. 2 depicts the graphene-drum pump 101 in exhaust mode. In theexhaust mode, the upstream valve 205 is closed and the downstream valve206 is opened, while the main diaphragm graphene drum 201 is beingpulled downward (such as due to a voltage between the main diaphragmgraphene drum 201 and metallic gate 203). This results in the fluid(such as air) being pumped from the cavity 202 through the downstreamvalve 205 and into the fluid output.

FIG. 3 depicts the graphene-drum pump 101 in intake mode. In the intakemode, the upstream valve 205 is opened and the downstream valve 206 isclosed, while the main diaphragm graphene drum 201 moves upward. (Forinstance, by reducing the voltage between the main diaphragm graphenedrum 201 and metallic gate 203, the graphene drum 201 will spring upwardbeyond its “relaxed” position). This results in the fluid (such as air)being drawn from the fluid source through the upstream valve 205 andinto the cavity 202.

To reduce or avoid wear of the upstream valve 205 that utilizes anupstream valve graphene drum 207, embodiments of the invention caninclude an upstream valve element 217 to sense the position between theupstream valve graphene drum 207 and bottom of cavity 210. Likewise toreduce or avoid wear of the downstream valve 206 that utilizes adownstream valve graphene drum 212, embodiments of the invention caninclude an downstream valve element 218 to sense the position betweenthe downstream valve graphene drum 212 and bottom of cavity 215. Thereason for this is because of the wear that upstream valve 205 anddownstream valve 206 will incur during cyclic operation, which can be onthe order of 100 trillion cycles during the device lifetime. Because ofsuch wear, upstream valve graphene drum 207 and downstream valvegraphene drum 212 cannot repeatedly hit down upon the channel openingsto conduit 209 and conduit 213, respectively.

As shown in FIG. 2, upstream valve element 217 is shown in thecenter/bottom of cavity 210 of the upper valve 205, and downstream valveelement 218 is shown in the center/bottom of cavity 215 of downstreamvalve 206. Upstream valve element 217 is used to sense the position ofthe upstream valve graphene drum 207 relative to the bottom of cavity210 by using extremely sensitive tunneling currents as feedback. Aseparate circuit (not shown) is connected between the upstream valveelement 217 and the upstream valve graphene drum 207. Likewisedownstream valve element 218 is used to sense the position of thedownstream valve graphene drum 207 relative to the bottom of cavity 215by using extremely sensitive tunneling currents as feedback. A separatecircuit (not shown) is connected between the upstream valve element 218and the upstream valve graphene drum 212.

With respect to the upstream valve 205, when the upstream valve graphenedrum 207 is within about 1 nm of the upstream valve element 217, asignificant tunneling current will flow between the upstream valvegraphene drum 205 and the upstream valve element 217. This current canbe used as feedback to control the voltage of upstream valve gate 211.When this current is too high, the gate voltage of upstream valve gate211 will be decreased. And, when this current is too low, the gatevoltage of upstream valve gate 211 will be increased (so that the valvestays in its “closed” position, as shown in FIG. 2, until it isinstructed to open). There will likely be a gap (around 0.5 nm) betweenthe upstream valve graphene drum 207 and channel opening to conduit 209when the upstream valve 205 is closed; this gap is so small that itprevents most fluid molecules from passing through the upstream valve205 yet the gap is large enough to avoid wear. For instance, in anembodiment of the invention, a resistor and voltage source (not shown)can be utilized. The resistor can be placed between the upstream valveelement 217 and the voltage source. When the upstream valve graphenedrum 207 comes within tunneling current distance (such as around 0.3 to1 nanometers) of upstream valve element 217, the tunneling current willflow through upstream valve graphene drum 207, upstream valve element217 and the resistor. This tunneling current in combination with theresistor will lower the voltage between upstream valve element 217 andupstream valve graphene drum 207, thus lowering the electrostatic forcebetween upstream valve element 217 and upstream valve graphene drum 207.If upstream valve graphene drum upstream valve graphene drum moves awayfrom upstream valve graphene 217, the tunneling current will drop andthe voltage/force between upstream valve graphene drum 207 and upstreamvalve element 217 will increase. Thus a 0.3 to 1 nanometer gap betweenupstream valve graphene drum 207 and upstream valve element 217 ismaintained passively which allows the valve to close without causingmechanical wear between upstream valve graphene drum 207 and upstreamvalve element 217.

With respect to downstream valve 206, downstream valve element 218 canbe utilized similarly.

In further embodiments, while not shown, standard silicon elements (suchas transistors) can be integrated within or near the insulating material103 near the respective graphene drums (main diaphragm graphene drum201, upstream valve graphene drum 207, or downstream valve graphene drum212) to help control the respective graphene drum and gate set.

In further embodiments, in lieu of using tunneling currents as feedback,the feedback can be the change in capacitance between upstream valvegraphene drum 207 and upstream valve gate 211. For instance, acapacitance sensor can be used to detecting the change of capacitance,which would be indicative of the location of the graphene drum.

Embodiments of the graphene-drum pump system 100 shown in FIG. 1 (andgraphene-drum pump 101 shown in FIGS. 2-3) as described above, can bemodified to operate as a graphene-drum internal combustion enginesystem. In such instance, the intake fluids from the fluid source caninclude a combustible fluid mixture (such as fuel and oxygen from theair). Furthermore, the opening and closing of the upstream valve 205 andthe downstream valve 206 are generally designed to operate independently(such that both valves can be closed at the same time).

The process by which the graphene-drum internal combustion engine systemoperates can be as follows.

Intake step: In the intake step, the combustible fluid mixture is placedin the combustion chamber. For example, similar to the pump intakeillustrated in FIG. 3, the upstream valve 205 is opened and thedownstream valve 206 is closed, while the main diaphragm graphene drum201 moves upward (such as reducing the voltage between the maindiaphragm graphene drum 201 and metallic gate 203). This results in thecombustible fluid mixture being drawn from the fluid source through theupstream valve 205 and into the cavity 202.

Compression step: In the compression step, the upstream valve 205 isclosed while maintaining the downstream valve 206 in the closedposition. The main diaphragm graphene drum 201 is then pulled downward(such as due to a voltage between the main diaphragm graphene drum 201and metallic gate 203). This results in compression of the combustiblefluid mixture in the cavity 202.

Ignition Step: In the ignition step, the combustible fluid mixture isignited. FIG. 4 depicts a graphene-drum internal combustion engine 400in the ignition mode. For instance, a metallic trace or via (connectedto a voltage source) can provide a high-voltage electrical spark toignite the combustible fluid mixture in the cavity 202. FIG. 4 depictsthe ignited combustible fluid mixture 401. This figure also depicts thatupstream valve 205 and the downstream valve 206 are generally closedduring the ignition step.

Instead of drawing in just air or some other fluid, the engine systemwould draw in an air-fuel mixture. Like conventional internal combustionengine, the graphene-drum internal combustion engine can compress thefuel-air mix until it reached ignition (or was set off by a sparkbetween main graphene drum and gate), the hot gas would then expandduring the power stroke and then, as discussed below, the exhaust pumpedout. Unlike a conventional internal combustion engine, the graphene-druminternal combustion engine can use the time-varying capacitance betweenthe graphene drum 201 and metallic gate 203 to extract electrical powerfrom system during power stroke. Compressing the fuel-air mixture isaccomplished by applying a voltage between graphene drum 201 andmetallic gate 203. This compression voltage can also be used to seed thetime-varying capacitance process needed for power extraction. The valveswould work in same manner as described for pump above.

This results in expansion of the combusted fluid mixture, which can thenbe used to produce useful work. Such expansion generally acts to coolthe combusted fluid mixture and vary the capacitance between metallicgate 203 and graphene drum 201. This time varying capacitance can beused along with external circuitry (not shown) to covert expansionforces into electrical energy.

Exhaust Step: In the exhaust step, the cooled combusted fluid mixture isexhausted. For example, similar to the pump exhaust illustrated in FIG.2, the upstream valve 205 is closed and the downstream valve 206 isopened, while the main diaphragm graphene drum 201 is being pulleddownward (such as due to a voltage between the main diaphragm graphenedrum 201 and metallic gate 203). This results in the cooled combustedfluid mixture being pumped from the cavity 202 through the downstreamvalve 206 and into the fluid output. Generally, the cooled combustedfluid mixture will ultimately be exhausted to atmosphere.

In other embodiments of the present invention, the graphene-drum pumpsystem is a graphene-drum Stirling engine system 501, such as depictedin FIG. 5. FIG. 6 depicts a side view of the graphene-drum Stirlingengine system of FIG. 5. Like a conventional Stirling engine, thegraphene-drum Stirling engine would use a temperature differential (asoriented in the FIG. 5-6, top part 501 of device 500 is kept hot, andbottom part 502 of device 500 cold) to drive the “pistons.” Device 500is sealed with a working gas (air, helium, etc.) that can move back andforth between the hot side 501 and the cool side 502. Like thegraphene-drum internal combustion engine described above, power would beextracted by seeding the gate with a voltage and then extracting poweras the graphene membrane pulled away from the gate. A piezoelectric filmin contact with the graphene drums might also be used to extract powerfrom the oscillating membranes. The metal 503 in the center of device500 is a heat exchanger that cools the working gas as it moves from hotside 501 to cool side 502 and heats the working gas as it moves fromcool side 502 to hot side 501. The hair-like structures 504 shown on thebottom of the device 500 can be carbon nanotubes or another kind ofthermally conductive nanowire to help keep cool side 502 cool(conventional thermal fins might also be used). Hot side 501 might be inthermal contact with a warm microprocessor to help cool and power theprocessor. Sunlight could be focused on hot side 501 to generateelectrical power at efficiencies that likely exceed photo voltaic cells.

The primary way to extract power from both internal combustion andStirling graphene-drum engines is by exploiting the fact that thecapacitance between the graphene drum and the gate varies with time. Ifa voltage is placed between the graphene drum and the gate (just beforethe graphene drum pulls away from the gate), a current will be generatedthat is proportional to this seed voltage times dC/dt (the time rate ofchange of graphene drum-gate capacitance). The energy output isproportional to the force to separate the graphene drum away from thegate times the distance of travel of the graphene drum. Extractingenergy from time-varying capacitors is further described in Miyazaki M.,et al., “Electric-Energy Generation Using Variable-Capacitive Resonatorfor Power-Free LSI: Efficiency Analysis and Fundamental Experiment,”International Symposium on Low Power Electronics and Design, Proceedingsof the 2003 International Symposium on Low Power Electronics and Design,193-198 (2003), which is incorporated herein by reference.

In FIGS. 7-8, an alternate embodiment of the present invention is shownthat locates the graphene drum 201 such that the cavity 202 (in FIG. 2)is separated into two sealed cavities. (The change of position ofgraphene drum 201 is shown in FIGS. 7-8). Per the orientation of FIGS.7-8, graphene drum 201 seals an upper cavity 701 and a lower cavity 702.As shown in FIGS. 7-8, upstream valve 205 and the downstream valve 206are positioned to allow the pumping of fluid in and out of upper cavity701.

As depicted in FIGS. 7-8, lower cavity 702 is oriented between thegraphene drum 201 and the gate 203. Lower cavity 702 can be evacuated toincrease the breakdown voltage between the graphene drum 201 and thegate 203. The maximum force (and thus the maximum graphene drumdisplacement) between the graphene drum 201 and the gate 203 increasesas the square of this voltage. Thus, the pumping speed of the device 700will increase significantly with an increase in the maximum allowablevoltage.

As noted above, upper cavity 701 can be filled with air or some othergas/fluid that is being pumped. The vacuum in the lower cavity 702 canbe created prior to mounting the graphene drum 201 over the main openingand maintained with a chemical getter. Small channels (not shown)between the lower cavities 702 could be routed to an external vacuumpump to create and maintain the vacuum. A set of dedicated graphene drumpumps mounted in the plurality of graphene drum pumps could also be usedto create and maintain vacuum in the lower chambers (since pumpingvolume is so low these dedicated graphene drum pumps could operate withair in their lower chambers).

Similar to other embodiments shown in this Application, in FIGS. 7-8,graphene drum 201 can act like a giant spring: i.e., once the gate 203pulls graphene down (as shown in FIG. 7), when released the graphenedrum 201 will spring upward (as shown in FIG. 8).

This same approach can also be used in internal combustion embodimentsto increase the power density of the device.

In FIG. 9, a further alternate embodiment of the present invention isshown. In The graphene-drum pump system 900 shown in FIG. 9 can beactuated without requiring feedback as described above with respect toFIG. 2. In this embodiment, non-conductive member 904 (such as oxide) isplaced between the graphene drum 201 and metallic gate 901 so that thegraphene drum 201 cannot go into runaway mode and so that graphene drum201 will not vigorously impact metallic gate 901 when seating. Inembodiments of the invention, setting the graphene drum 201(non-deflected) to metallic gate 901 distance to 20% of the diameter ofthe graphene drum 201 will prevent runaway (for a maximum deflectionthat is in the order of 10% of diameter of the graphene drum 201) andwill allow the graphene drum 201 to seat softly on a surface of thenon-conductive member 904 (such as oxide) without the need for feedback.

As shown in FIG. 9, when the graphene drum 201 is an open position,fluid can flow either (a) in inlet/outlet 902, through cavity 202, andout outlet/inlet 903 or (b) in outlet/inlet 903, through cavity 202, andout inlet/outlet 902 (due to the pressure differential betweeninlet/outlet 902 and outlet/inlet 903).

As shown in FIG. 9, the metallic gate 901 and metallic trace 905 have anon-conductive member 904 (such as oxide) between them. A voltage source907 can be placed between the metallic gate 901 and the metallic trace905 operatively connected to the graphene drum 201. The non-conductivemember 904 physically prevents the graphene drum 201 and the metallicgate 901 from coming in contact with one another. This would preventpotentially damaging impacts of the graphene drum 201 and metallic gate901.

While not illustrated, in further embodiments of the invention, thegraphene-drum pump system can be designed to prevent the graphene drumand metallic gate from coming in contact. For instance, the graphenedrum could be located at a distance such that its stiffness thatprecludes the graphene drum from being deflected to the degree necessaryfor it to come in contact with metallic gate. In such instance, thegraphene drum would still need to be located such that it can be in theopen position and the closed position. Or, a second and stabilizingsystem can be included in the embodiment of the invention that isoperable for preventing the graphene drum from coming in contact withthe gate.

As noted above, embodiments of the present invention can be used as apump to displace fluid. This includes the use of present invention in aspeaker, such as a compact audio speaker. While the graphene drums inthe present invention operate in the MHz range (i.e., at least about 1MHz), the graphene drums can produce kHz audio signal by displacing airfrom one side and pushing it out the other (and then reversing thedirection of the flow of fluid at the audio frequency). Advantages ofutilizing such an approach include: (a) this will provide the ability tomake very low and very high pitch sounds with the same and very compactspeaker; (b) this will provide the ability to make high volume soundswith a very small/light speaker chip; and (c) this will provide a littlegraphene speaker that would cool itself with high velocity airflow.

Furthermore, the present invention can be utilized in other devices andsystems to take advantageous of the small size and precise fluid flow ofthe graphene-drum pump. For instance, the small size and precise fluidflow of the graphene-drum pump renders it useful in medical applications(such as drug delivery, miniature heart pumps, etc.) and consumerelectronics applications (such as tiny ink pumps, silent fans etc.).

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

While embodiments of the invention have been shown and described,modifications thereof can be made by one skilled in the art withoutdeparting from the spirit and teachings of the invention. Theembodiments described and the examples provided herein are exemplaryonly, and are not intended to be limiting. Many variations andmodifications of the invention disclosed herein are possible and arewithin the scope of the invention. For example, graphene-drum pumps andengines can be layered or stacked (for instance, vertically) to increaseoutput. Also, the graphene drums can be shapes other than circles suchas squares or rectangles (i.e., the use of the term “drums” does notlimit the shape). Accordingly, other embodiments are within the scope ofthe following claims. The scope of protection is not limited by thedescription set out above, but is only limited by the claims whichfollow, that scope including all equivalents of the subject matter ofthe claims.

The disclosures of all patents, patent applications, and publicationscited herein are hereby incorporated herein by reference in theirentirety, to the extent that they provide exemplary, procedural, orother details supplementary to those set forth herein

1. A pump comprising: (i) a cavity having a diaphragm, wherein thediaphragm is operable to change the volume capacity of the cavity; (ii)an upstream valve connected to the cavity, wherein (a) the upstreamvalve is operable to be in an open position, wherein fluid can flowthrough the upstream valve into the cavity, and (b) the upstream valveis operable to be in a closed position, wherein fluid cannot flowthrough the upstream valve into the cavity; and (iii) a downstream valveconnected to the cavity, wherein (a) the downstream valve is operable tobe in an open position, wherein fluid can flow from the cavity throughthe downstream valve, and (b) the downstream valve is operable to be ina closed position, wherein fluid cannot flow from the cavity through thedownstream valve, wherein at least one of the cavity, upstream valve, ordownstream valve comprises an electrically conductive drum, wherein theelectrically conductive drum is atomically thin. 2-5. (canceled)
 6. Thepump of claim 1, wherein the electrically conductive drum is a graphenedrum. 7-8. (canceled)
 9. The pump of claim 1, wherein at least one ofthe cavity, upstream valve, or downstream valve comprises a multielectrically-conductive-drum stack of at least two electricallyconductive drums. 10-13. (canceled)
 14. The pump of claim 1, wherein thecavity comprises a first electrically conductive drum, the upstreamvalve comprises a second electrically conductive drum, and thedownstream valve comprises a third electrically conductive drum. 15.(canceled)
 16. The pump of claim 14, wherein (a) the first electricallyconductive drum is a first graphene drum, (b) the second electricallyconductive drum is a second graphene drum, and (c) the thirdelectrically conductive drum is a third graphene drum.
 17. The pump ofclaim 1 further comprising a electrically conductive gate, wherein theelectrically conductive drum is operable to be pulled toward theelectrically conductive gate due to a voltage between the electricallyconductive drum and the electrically conductive.
 18. (canceled)
 19. Thepump of claim 1, wherein the diaphragm is the electrically conductivedrum. 20-21. (canceled)
 22. The pump of claim 19 further comprising (i)a second cavity, wherein (a) the diaphragm is operable to change thevolume capacity of the second cavity, (b) as the volume capacity of thecavity increases the volume capacity of the second cavity decreases, and(c) as the volume capacity of the cavity decreases the volume capacityof the second cavity increases. (ii) a metallic gate located within thesecond cavity, wherein the electrically conductive drum is operable tobe pulled toward the electrically conductive gate due to a voltagebetween the electrically conductive drum and the electrically conductivegate. 23-46. (canceled)
 47. A valve comprising: (i) a cavity having (a)an electrically conductive membrane, and (b) an opening for flowingfluid though the cavity; (ii) a gate operable to move the electricallyconductive membrane between a first position and second position due toa change in voltage applied to the gate, wherein (a) when theelectrically conductive membrane is in the first position, theelectrically conductive membrane is located away from the opening suchthat fluid can flow freely through the opening, and (b) when theelectrically conductive membrane is in the second position, theelectrically conductive membrane is located at a predetermined distancefrom the opening such that fluid flow though the opening is restricted.48. The valve of claim 47, further comprising an electrical conductorlocated near the opening, wherein when the electrically conductivemembrane is located at or near the second position, the electricalconductor and electrically conductive membrane are operatively connectedto allow a current to flow therebetween that is indicative of thelocation of the electrically conductive membrane.
 49. The valve of claim48, further comprising a controller operable to control the voltageapplied to the gate by utilizing the current to adjust the gate voltageso that the electrically conductive membrane is located at the secondposition.
 50. The valve of claim 48, wherein the current is a tunnelingcurrent.
 51. The valve of claim 48 further comprising a resistor and avoltage source operatively connected to the electrically conductivemembrane and the gate, wherein when the electrically conductive membraneis located near the second position, a current can operatively flowthrough the resistor that passively lowers the voltage between theelectrically conductive membrane and the gate.
 52. The valve of claim 47further comprising a capacitor sensor operatively connected to theelectrically conductive membrane and the gate such that it may detect achange of capacitance between the electrically conductive membrane andthe gate that is indicative of the location of the electricallyconductive membrane.
 53. (canceled)
 54. The valve of claim 47, whereinthe valve is operable to prevent the electrically conductive member fromcoming in contact with the gate. 55-57. (canceled)
 58. The valve ofclaim 47, wherein the electrically conductive membrane is a graphenemembrane.
 59. The valve of claim 47, wherein the predetermined distanceis about 1 nm. 60-69. (canceled)
 70. A device that comprises a pump,wherein the pump comprises: (i) a cavity having a diaphragm, wherein thediaphragm is operable to change the volume capacity of the cavity; (ii)a first valve connected to the cavity, wherein (a) the first valve isoperable to be in an open position, wherein fluid can flow (I) throughthe first valve into the cavity and (II) from the cavity through thefirst valve, depending upon the pressure differential across the firstvalve, and (b) the first valve is operable to be in a closed position,wherein fluid cannot flow (I) through the first valve into the cavityand (II) from the cavity through the first valve, regardless of thepressure differential across the first valve; and (iii) a second valveconnected to the cavity, wherein (a) the second valve is operable to bein an open position, wherein fluid can flow (I) through the second valveinto the cavity and (II) from the cavity through the second valve,depending upon the pressure differential across the second valve, and(b) the second valve is operable to be in a closed position, whereinfluid cannot flow (I) through the second valve into the cavity and (II)from the cavity through the second valve, regardless of the pressuredifferential across the second valve; wherein at least one of thecavity, first valve, or second valve comprises an electricallyconductive drum, wherein the electrically conductive drum is atomicallythin.
 71. The device of claim 70, wherein the device is operable as aspeaker.
 72. The device of claim 71, wherein the device is operable as acompact audio speaker.
 73. The device of claim 70, wherein theelectrically conductive drum is a graphene drum.
 74. The device of claim73, wherein the graphene drum is operable for producing an audio signalhaving a frequency in the audio frequency range.
 75. (canceled)
 76. Thedevice of claim 74, wherein the graphene drum is operable for producingan audio signal having a frequency in the audio frequency range byalternating the flow of air through the pump in a first direction and asecond direction, wherein (a) the first direction of the air flow isflowing the air through the first valve, into and through the cavity,and through the second valve, (b) the second direction of the air flowis flowing air through the second valve, into and through the cavity,and through the first valve, and (c) the rate of alternating the flow ofair is the frequency of the audio signal.
 77. The device of claim 70,wherein the device is operable for medical applications. 78-79.(canceled)
 80. The device of claim 70, wherein the device is operablefor electronic applications. 81-84. (canceled)